DETROIT, Aug 20 — When it comes to alternative energy sources like solar power, other countries like Canada are way ahead of the U.S. — in part because power is relatively cheap here. Still, companies big and small really are committed to promoting solar power.

THE SUN is a limitless source of light, heat and energy. From big oil giants to cell phone makers, companies are trying to harness the sun’s glow. At Evergreen Solar in Marlboro, Mass., they’ve found a way to make solar panels using a process that makes more efficient use of silicon that their competitors.

“We’re pulling silicon out of a molten bath,” said Evergreen Solar CEO Mark Farber. “So we don’t have to slice a block of solid silicon and waste it like our competition does.”

The so-called “string ribbon” technology uses two heated strings to form a ribbon of molten silicon, which yields over twice as many solar cells per pound of silicon as conventional methods, according to the company’s Web site.

As with most forms of alternative energy, the key barrier to wider acceptance of solar power is cost. At Evergreen the same number of employees are turning out twice as many solar panels as they were a year ago. That’s because they’ve developed a machine that can produce two silicon ribbons instead of one. But all this technology has yet to yield profits.

“Their technology seems promising, but it is still an unprofitable company that is burning cash,” said David Kurzman, an industry analyst at HC Wainwright in South Hamilton, MA.

Lack of profits is also the reason you won’t see big oil companies pushing solar energy beyond the lab. Only the small companies dare to bring the sun to consumers — companies like Energy Conversion Devices, which is struggling to make a buck. Analysts say the problem is cost.

“Solar is still relatively expensive compared to other types of base-load power,” said Kurzman. “For instance, solar power at this point is around 25 cents per kilowatt hour.”

That’s four times the cost of power coming from the average utility.

In some states, government “green funds” will offset half the initial cost. But even with the subsidy, suburban Boston homeowner George Cole paid $9,000 to install solar panels — a cost he may never recoup. And his panels provide only a fraction of the home’s energy needs.

“Without the incentive, we would not have been able to do this — not this year, not the next,” he said. “It was crucial to us.”

The extra cost is a tough sell — even for makers of solar panels like Evergreen.

“On [our] building we do not [have solar panels],” said Farber. “We are very busy selling the product we make to customers. We do expect to put panels on the building someday but we frankly haven’t gotten to it yet.”